1. Field of the Invention
The present invention relates generally to a mobile wireless communication terminal and, in particular, to an antenna apparatus for use in mobile wireless communication terminals such as mobile phones, hand-held personal computers, personal digital assistants (PDAs), etc.
2. Description of the Related Art
In recent years, mobile communication systems that are in common use by a great number of mobile subscribers have extended their available services to include paging service, mobile phone calling, short message service (SMS) to a mobile banking service system, and further up to a multi-media service such as motion picture service and the like. The tremendous growth of the mobile communication systems with a diversity of service functions has led to the need to make more use of an integrated type of wireless terminal devices such as PDAs and the like, which serve as both a personal computer and a mobile communication terminal equipment, e.g. mobile phone, because a conventional mobile phone is to some degree limited in the extent of its functions.
Referring to FIG. 1, there is shown a schematic front view of a conventional mobile communication terminal 100, that is to say, e.g. a PDA. As seen in the front view, the mobile communication terminal 100 is provided with a display unit 101 in its front, under which a keypad assembly 105 is arranged and above which a speaker 109 is disposed. As the keypad generally has a limit in the scope of data capable of inputting as an input means, the display unit 101 may be implemented as an input device using a touch screen. On one side of an upper end of the mobile terminal 100 is disposed an antenna 107 and on an other side of the upper end of the mobile terminal 100 is disposed a camera module 111, of which photographing angle is adjustable by an adjusting knob 113 disposed on one side of the upper end of the mobile terminal 100 and adjacent to the camera module 111.
Referring then to FIGS. 2 and 3, the keypad 105 is comprised of a silicon keypad 151 provided with a plurality of key buttons 151a projecting to the outside of the mobile terminal 100, and a flexible printed circuit board 153 for the keypad. The flexible printed circuit board 153 is provided with electrical contacts corresponding to the plurality of key buttons 151a and is adapted to generate a set of electrical signals S for supplying to a main board 157 of the mobile terminal according to the manipulation of the key buttons 151a by a user. The flexible printed circuit board 153 is connected to a data cable 153b for transferring the electrical signal S to the main board 157. The keypad is disposed on a cover 155 mounted to protect the main board 157. Further, a respective key button 151a of the silicon keypad 151 may be preferably attached at its upper surface to a plastic material (not sown) or the like for offering more pleasant touch to the users.
In the meantime, the tremendous increase of data and information transferred using the mobile communication terminal, as during a multi-media content service, essentially demands high-speed data transmission in the mobile communication service system. Hence, a diversity antenna has been proposed in the art as one preferred solution for improving the data transfer rate as well as the quality of data transfer.
Referring now to FIG. 4, which illustrates a front view of a mobile wireless communication terminal 200, e.g. a PDA, with such a diversity antenna 203 of the prior art, being further provided with an additional, second antenna 203 mainly used for the diversity receiving function. The front surface of the mobile terminal 200 includes a display unit 201, below which display unit 201 and keypad assembly 205 are disposed, and above which a speaker 209 is disposed. On one side of the upper end of the mobile terminal 200 is positioned a first antenna 207 for a general transmitting/receiving function, while on the other side of the upper end the second diversity antenna 203 is positioned for the diversity receiving function. Here, the second diversity antenna 203 in the signal receiving operation of the mobile terminal serves to prevent fading phenomena by means of receiving radio waves separately from the first antenna, wherein the fading phenomenon is referred to as a physical phenomenon that significant degradation of signal strength or quality, or transfer rate or the like that is mainly owing to the physical change in medium through which radio waves pass, the diffraction of radio waves or the phase difference between more than one receiving path of the radio waves transmitted from the same origination. That is to say, a combination of two signals each received through the first and second antennas 207 and 203 enables effective detection of an optimal receiving signal, so as to prevent the fading phenomenon to obtain better quality of signal. This will also be quite helpful to achieve remarkable improvement of transfer rate in the mobile communication system.
Meanwhile, FIG. 5 shows a front view of a mobile wireless communication terminal 300, e.g. a PDA, with the diversity receiving antenna 303 arranged in such a way that it extends downwardly from the opposite, i.e. lower, end of the mobile terminal 300, so that the second antenna is positioned apart from the first antenna 307 enough to carry out the diversity receiving function efficiently. The remaining components of the mobile terminal 300, inclusive of a display unit 301, a keypad assembly 305, a speaker 309, a camera module 311 and so on, may be arranged in a similar way to the foregoing construction described with reference to FIGS. 1 to 4.
However, the conventional type of mobile communication terminal as described above has a disadvantage that it may be not only inconvenient for some users to carry owing to such a protrusion of the second antenna from a main body of the mobile communication terminal, but also it may be subject to damage should the user happen to drop it down onto a hard floor carelessly. Further, such an antenna apparatus has some degree of limitation in design since it has a protrusion part extending outwardly from the main body of the mobile terminal. Furthermore, in the design of the mobile communication terminal with the diversity antenna apparatus, it will technically not be easy for a designer to ensure a space for adequately accommodating the diversity antenna apparatus inside the mobile communication terminal because its interior parts are essentially to be configured very compactly in a limited spacing.